let D be set ; for p, q being Element of D ^omega holds FlattenSeq <%p,q%> = p ^ q
let p, q be Element of D ^omega ; FlattenSeq <%p,q%> = p ^ q
consider g being BinOp of (D ^omega) such that
A1:
for d1, d2 being Element of D ^omega holds g . (d1,d2) = d1 ^ d2
and
A2:
FlattenSeq <%p,q%> = g "**" <%p,q%>
by Def10;
thus FlattenSeq <%p,q%> =
g . (p,q)
by A2, Th38
.=
p ^ q
by A1
; verum